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SOME SIMPLE IR PROBLEMS

SOME SIMPLE IR PROBLEMS. Assign all the peaks that you can (that is, label them right on the spectrum) with the type of bond responsible for the absorption: C=O, C-H, -CH 2 - or -CH 3 bending, N-H, O-H, C-O, -C=N, C=C, benzene, oops, etc.). =.

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SOME SIMPLE IR PROBLEMS

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  1. SOME SIMPLE IR PROBLEMS Assign all the peaks that you can (that is, label them right on the spectrum) with the type of bond responsible for the absorption: C=O, C-H, -CH2- or -CH3 bending, N-H, O-H, C-O, -C=N, C=C, benzene, oops, etc.). = Unless otherwise noted, a bond designation implies stretching - bending and oops must be specifically noted. For instance, “C=O” or “C-H” imply stretching. These can be solved using infrared and an index of hydrogen deficiency.

  2. Problem 1 HINT: Can be made from propyne when treated with aqueous H2SO4 and HgSO4. C3H6O 1421 1363 1715

  3. Problem 2 HINT: Can be made from ethyl iodide and a good nucleophile in acetone (SN2). C3H5N 2248

  4. Problem 3 HINT: Made by adding water to propene using 3M H2SO4. C3H8O 1162 3345 1130 970

  5. Problem 4 HINT: The solution to this one is in the hydrogen deficiency index. C5H10O 1162 994 3345

  6. Problem 5 HINT: The solution to this one is in the hydrogen deficiency index. C7H5N 2178

  7. Problem 6 HINT: The solution to this one is in the hydrogen deficiency index. C8H8O 1686

  8. Problem 7 HINT: This one stinks like rancid butter. C4H8O2 1712

  9. Problem 8 HINT: There are two functional groups. C3H4O 2121

  10. Problem 9 HINT: The two peaks at 2820 and 2738 are the key. C7H6O 2738 2820 1703

  11. Problem 10 C8H8O2 1112 1724 1279

  12. PRACTICAL APPLICATION This next problem is a little more difficult, requiring both infrared and a knowledge of reactions.

  13. Problem 11 As a project, Mary was given an unknown compound A, and told to perform the reactions listed below. At the end of each reaction step she was told to submit the major product for microanalysis, in order to obtain the molecular formula, and to also determine its infrared spectrum. The structure of each compound was to be identified. Can you help her solve the structures and pass this class? A B C H2SO4/HgSO4 Ni / H2 C8H6 C8H8O C8H10O 2 atm H2O TsCl pyridine NaCN Spectra are on the pages that follow. acetone Ni / H2 C9H13N C9H9N 2 atm E D

  14. A C8H6 2110 3310

  15. C8H8O B 1686

  16. C8H10O C 3353

  17. C9H9N D 2243

  18. C9H13N E 3374 3293

  19. Also check out Problems 74 and 75 at the end of Chapter 12. You should able to solve these now that we have finished Chapter 11.

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